1. Field of the Invention
The present invention relates to a disk cartridge which rotatably accommodates a disc-shaped disk medium used as a recording/playback medium of an information processing device or the like, and which is equipped with a shutter for opening and closing an opening provided at the disk cartridge.
Further, the present invention relates to a disk cartridge which rotatably accommodates a disc-shaped disk medium used as a recording/playback medium of an information processing device or the like, and which prevents entry of dust or the like.
2. Description of the Related Art
A disc-shaped disk medium, such as an optical disk, a magneto-optical disk, or the like, is used, for example, as a portable recording/playback medium for a computer. When recording or playback of the disk medium is carried out, laser light is illuminated onto the recording surface while the disk medium is rotated in a state of being loaded in a drive device. In this way, recording of information is carried out by pit formation or phase changes due to decomposition of the dye layers of the recording surface, or by magnetization or the like, or recorded information is played back on the basis of differences in the reflectivity or the polarizing angle of the laser light.
Further, in such disk media, shortening of the wavelength of the laser light which is illuminated onto the recording surface has been proposed in order to increase the recording capacity. When recording or playback of information is carried out by using this short-wavelength laser light (e.g., a violet color laser), in order to suppress the attenuation of the laser light due to a cover layer which protects the recording surface of the disk medium, the cover layer must be made thin. By making the cover layer thin in this way, the diameter of the laser light at the surface of the cover layer (the surface which is exposed to the exterior) decreases, and it is not possible to ignore the effects of dust and the like adhering to the surface of the cover layer.
Thus, disk cartridges, which accommodate a disk medium in a case and prevent adhesion of dust or the like onto the disk medium, are employed. Such a disk cartridge is formed to include an opening and a shutter member. The opening is for exposing to the exterior a center hole portion provided at the central portion of the disk medium, and a portion of the recording surface (the cover layer). The shutter member opens and closes this opening.
In this way, in the disk cartridge, by closing the opening by the shutter member when the disk medium is not in use, entry of dust or the like into the disk cartridge (i.e., adhesion of dust or the like onto the disk medium) is prevented. At the time when the disk medium is used, by opening the opening as the disk cartridge is loaded into the drive device, the center hole portion can be held by a rotation spindle shaft, and the laser head can approach the recording surface (laser light can be illuminated).
However, in the above-described disk cartridge, a space for accommodating the shutter member when the opening is in the aforementioned open state must be ensured, and a problem arises in that it is difficult to make the disk cartridge more compact.
Thus, to aim for compactness, disk cartridges in which the shutter member is divided in two have been disclosed. (One example is Japanese Patent Application Laid-Open (JP-A) No. 2000-30394.) Hereinafter, the disk cartridge disclosed in this publication will be described on the basis of FIG. 44.
In FIG. 44, a disk cartridge 400 is illustrated in an exploded perspective view. As shown in this figure, the disk cartridge 400 is structured such that a disc-shaped disk medium 406 is rotatably accommodated within a case which is formed by joining a top shell 402 and a bottom shell 404 which are respectively formed of a resin material.
A tubular wall 404A, which serves as an inner wall and at whose inner side the disk medium 406 is accommodated, and an opening 408, which is cut-out from the front portion of the tubular wall 404A to the substantially central portion of the bottom shell 404, are provided at the bottom shell 404.
The opening 408 is formed by an opening 408A and an opening 408B communicating with one another. The opening 408A is for insertion (approach) of a laser head along the radial direction of the disk medium 406. The opening 408B corresponds to a center hole portion 406A of the disk medium 406, and is for insertion of a rotation spindle shaft. The opening 408 is for accessing the disk medium 406.
The disk cartridge 400 is provided with a first shutter member 410 and a second shutter member 412 for opening and closing the opening 408. The first shutter member 410 is formed to include a shutter main body 414 and a shutter guide portion 416. The shutter main body 414 is formed in a substantially trapezoidal shape, and mainly opens and closes the opening 408A. The shutter guide portion 416 stands erect at the front end of the shutter main body 414, is formed in a circular-arc shape corresponding to the tubular wall 404A, is guided by the tubular wall 404A, and opens and closes the front portion cut-out portion of the tubular wall 404A (i.e., the rising portion of the opening 408A).
Further, a thin-plate-shaped connecting portion 418, which is deformable in the direction of the plate thickness thereof, is connected to one end portion of the shutter guide portion 416. A block-shaped operation portion 418A is provided at the distal end of the connecting portion 418. The shutter guide portion 416 and the connecting portion 418 are connected together by being molded integrally, or by, after being manufactured as separate members, being fixed together by adhesion, welding, pressure-connecting, or the like. The tensile force (operational force) applied to the connecting portion 418 is transferred to the shutter guide portion 416 such that the shutter guide portion 416 rotates.
The second shutter member 412 is formed in an elongated trapezoidal shape, and rotates around a rotation shaft 412C provided at an end portion thereof so as to mainly open and close the opening 408B. A pin 412D serving as a spring catch is provided erect in a vicinity of the rotation shaft 412C of the second shutter member 412. The rotation shaft 412C and the pin 412D are inserted, from the under side, through a shaft hole 404B and a guide hole 404C, respectively, of the bottom shell 404, and are positioned at the outer side of the tubular wall 404A in the bottom shell 404.
In this state, the rotation shaft 412C is inserted through an annular portion of a torsion spring 419, and a short rod portion of the torsion spring 419 catches on the pin 412D. Due to a long rod portion of the torsion spring 419 abutting on an appropriate position of the bottom shell 404, the second shutter member 412 is urged in a direction of closing the opening 408B. The disk cartridge 400 is provided with a cover member 420. The first and second shutter members 410, 412 are movably accommodated between the cover member 420 and the bottom shell 404 (the case). An opening 422, which is for access to the disk medium 406 and which corresponds to the opening 408, is formed in the cover member 420.
At the disk cartridge 400, when the disk medium 406 is not in use, respective end surfaces 414A, 412A of the shutter main body 414 of the first shutter member 410 and the second shutter member 412 abut one another so as to close the openings 408, 422. Specifically, the first shutter member 410 mainly closes the opening 408A, and the second shutter member 412 mainly closes the opening 408B. Further, in this state, the shutter guide portion 416 of the first shutter member 410 closes the rising portion of the opening 408A (the cut-out portion of the tubular wall 404A front portion). On the other hand, when the disk medium 406 is to be used, the disk cartridge 400 is loaded into a drive device. The end surfaces 414A, 412A of the first and second shutter members 410, 412 are moved in directions of separating from one another, and open the openings 408, 422.
Specifically, when, accompanying the loading of the disk cartridge 400 into the drive device, the operation portion 418A, which is fixed to the distal end of the connecting portion 418 of the first shutter member 410, is moved in the direction of arrow P along a guide groove 424 of the case side surface (i.e., when the connecting portion 418 is pulled), while the shutter guide portion 416 is guided along the outer peripheral surface of the tubular wall 404A, the shutter main body 414 of the first shutter member 410 rotates in the direction of arrow Q around the axial center of the tubular wall 404A (i.e., the disk medium 406).
Accompanying this rotation, the first shutter member 410, at a convex portion 414B thereof which is positioned along the end surface 414A thereof, pushes an engaging portion 412B, which is positioned along the end surface 412A of the second shutter member 412. The second shutter member 412 is rotated in the direction of arrow R around the rotation shaft 412C. Namely, the first shutter member 410 and the second shutter member 412, while operating interlockingly, rotate in different directions so as to open the openings 408, 422. In this state, a window portion 416A provided at the shutter guide portion 416 is positioned at the front portion of the tubular wall 404A and opens the cut-out portion of the tubular wall 404A (the opening 408A).
At this time, the shutter main body 414 of the first shutter member 410 and the second shutter member 412 slide along a concave portion for sliding (not illustrated) which is formed in the bottom surface of the bottom shell 404. Further, the shutter guide portion 416 of the first shutter member 410 slides along the tubular wall 404A. Moreover, because the first shutter member 410 and the second shutter member 412 to rotate in different directions, the convex portion 414B and the engaging portion 412B, which make the first shutter member 410 and the second shutter member 412 operate interlockingly, are slid along each other.
In the disk cartridge 400, the convex portion 414B of the first shutter member 410 (the shutter main body 414), which pushes the engaging portion 412B of the second shutter member 412 while rotating around the axial center of the tubular wall 404A (the disk medium 406), is provided so as to be separated from the axial center of the tubular wall 404A, which is the center of rotation thereof, in order to make the second shutter member 412 rotate to a position of opening the opening 408B (in order to ensure the pushing stroke) by pushing which accompanies a predetermined amount of rotation of the first shutter member 410.
On the other hand, at the time when the openings 408, 422 which have been opened are to be closed again, either the operation portion 418A is pushed in the direction opposite to the direction of arrow P by a drive device, or the first shutter member 410 is pushed, at the convex portion 414B thereof, by the engaging portion 412B of the second shutter member 412 due to the urging force of the torsion spring 419. The first and second shutter members 410, 412 respectively rotate in directions of closing the opening 408 and the like (in directions opposite to the directions of arrow Q and arrow R), and the openings 408, 422 are closed.
In this way, the first shutter member 410 and the second shutter member 412 are accommodated in an accommodating space which substantially corresponds to the projected surface area of the disc-shaped disk medium 406, and the disk cartridge 400 can be made more compact. Further, the disk cartridge 400 can be made thinner because the first shutter member 410 and the second shutter member 412 are disposed in the same plane and close the openings 408, 422 by the respective end surfaces thereof abutting one another as was described above.
In assembling the disk cartridge 400, in the state in which the opening 408 of the bottom shell 404 is closed by the shutter members 410, 412, the disk medium 406 is accommodated (set) at the inner side of the tubular wall 404A of the bottom shell 404, and the top portion thereof is covered by the top shell 402. Next, after respective parts such as a locking means (not shown) and the like are assembled, the bottom portion of the bottom shell 404 (the case) is covered by the cover member 420.
However, there are the following problems with the above-described conventional disk cartridge 400.
First, at the first shutter member 410, the convex portion 414B, which is disposed at a position which is set apart from the axial center of the tubular wall 404A as described above, is provided (the position thereof is ensured) by a simple structure. Thus, the widthwise dimension (the dimension W shown in FIG. 44) of the shutter main body 414 is wider (by the amount required for providing the convex portion 414B) than a dimension which is sufficient for closing the opening 408A. The convex portion 414B, which corresponds to the end surface 414A, is provided at this portion where the width has been made greater.
Thus, problems arise in that the weight of the first shutter member 410 increases and the surface area for sliding along the bottom shell 404 (the case) increases and the sliding resistance increases, by an amount corresponding to the amount by which the shutter main body 414 has been made wider.
Further, the second shutter member 412 is an elongated structure in which the rotation shaft 412C, which is provided at one end portion of the second shutter member 412, and the opening 408B (the central portion of the case), which the second shutter member 412 mainly opens and closes, are set apart from one another. Problems arise in that the weight of the second shutter member 412 is large, the surface area for sliding along the bottom shell 404 (the case) at the time of opening and closing the opening 408 is large, and the sliding resistance also is great.
When the sliding resistance between, on the one hand, the first shutter member 410 and the second shutter member 412, and, on the other hand, the bottom shell 404 (the case) is great, and/or the respective weights of the shutter members 410, 412 are large, the driving force for opening and closing the opening 408 is large.
When the driving force for opening and closing the opening 408 is large, not only is smooth operation of the first shutter member 410 and the second shutter member 412 impeded, but also, it is necessary to improve the strength of the respective portions of the first shutter member 410 (including the connecting portion 418 and the operation portion 418A), which results in higher costs.
Moreover, when the driving force for opening and closing the opening 408 is large, it is a cause of deformation, such as buckling or the like, occurring at the thin-plate-shaped connecting portion 418 in the structure of pushing the operation portion 418A in the direction opposite to the direction of arrow P at the time of closing the opening 408. In the structure utilizing the urging force of the torsion spring 419 which urges the second shutter member 412 at the time of closing the opening 408, the urging force of the torsion spring 419 must be made stronger (the spring constant must be increased).
When the urging force of the torsion spring 419 is made stronger (i.e., when the spring constant is increased), handling of the torsion spring 419 is complicated, and assemblability is poor. In particular, at the disk cartridge 400, the urging force of the torsion spring 419 is applied to the pin 412D in a vicinity of the rotation shaft 412C of the second shutter member 412. Thus, the rotation moment, in the direction of closing the opening 408, of the second shutter member 412 due to this urging force is small, and the spring constant must be increased even more. Thus, this problem (of the assemblability and the like being poor) becomes marked, and the torsion spring 419 itself must be made larger. Either the disk cartridge 400 is made larger on the whole, or the regions of operation of the shutter members 410, 412 are made smaller (i.e., the opening 408 is made smaller and large-sized laser heads or the like cannot be handled).
Further, when the weight of the second shutter member 412 is large, in a case in which, for example, the disk cartridge 400 is dropped by accident, an extremely large load is applied to the rotation shaft 412C which may cause deformation or breakage of the rotation shaft 412C.
In particular, when the second shutter member 412 is made of a metal material in consideration of ensuring the flatness of the second shutter member 412 or preventing deformation due to temperature, the above-described problems relating to weight and sliding resistance become marked.
Here, forming at least one of the first shutter member 410 (the shutter main body 414) and the second shutter member 412 from a resin material in order to improve the slidability and lower the weight, has been contemplated. However, the surface areas of the shutter members 410, 412 are large. Therefore, at the thicknesses required of the shutter members 410, 412 in order to make the disk cartridge 400 more thin (i.e., values approaching minimum thicknesses which can be obtained by ordinary injection molding), there are cases in which warping which is not of an allowable extent (i.e., which impedes the operations of opening and closing the opening) arises at the shutter members 410, 412 due to residual stress at the time of molding. This problem becomes marked in particular in cases in which there are portions of non-uniform thickness at the shutter members 410, 412 (e.g., in cases in which the convex portion 414B and the pin 412D are molded integrally or in cases in which ribs or the like are provided).
Thus, in order to correct (prevent or suppress) warping of the shutter members 410, 412, insert molding which utilizes thin metal plates has been contemplated. However, because it is difficult to join metal and resin, it is necessary to form an embedded structure in which holes or concave portions are provided in the metal plate. However, when such an embedded structure is employed, the thickness of the resin layer is not uniform, and the residual stress is great. Thus, the resin layer may peel off in portions from the metal plate or cracks may arise, which causes poor operations for opening and closing the opening 408 and a deterioration in yield at the time of production.
Second, in order for the second shutter member 412 to also close a portion of the opening 408A for insertion of a laser head in the state in which the second shutter member 412 abuts the first shutter member 410, a sharp corner portion 412E is formed at the position of the second shutter member 412 which is furthest away from the rotation shaft 412C.
There is therefore the concern that, accompanying the above-described rotation, the sharp corner portion 412E may slide along the resin-made, lower shell 404 (the case) or the resin-made, cover member 420, and cause abrasion. Further, in the same way as the sharp corner portion 412E, there is also the concern that the other corner portions of the second shutter member 412 will abrade the case or the cover member 420 as they slide therealong.
In particular, the second shutter member 412 is formed so as to be elongated from a corner portion (the portion where the shaft hole 404B for rotatably supporting the rotation shaft 412C is provided) of the bottom shell 404 (the case) to the central portion thereof (the portion where the opening 408B is formed). Thus, it is easy for the second shutter member 412 to warp due to curling of the material or residual stress at the time of molding, and there is a great concern that abrasion will occur due to the aforementioned sliding.
Abrading of the bottom shell 404 or the cover member 420 not only impedes smooth operation of the second shutter member 412, but also is a cause of drop-out of the recording or playback signal when powder is formed due to the abrasion and this abraded powder adheres to the recording surface (the cover surface) of the disk medium 406.
Third, when the first shutter member 410 and the second shutter member 412 are formed of the same type of material, abrasion arises at the region of abutment (pushing) of the convex portion 414B of the first shutter member 410 and the engaging portion 412B of the second shutter member 412 which slide along each other at the time of opening and closing the opening 408. In the same way as with the above-described second problem, if powder formed by this abrasion adheres to the recording surface (the cover surface) of the disk medium 406, it becomes a cause of drop-out of the recording or playback signal.
In particular, if the first shutter member 410 and the second shutter member 412 are both formed of a metal material in order to ensure the flatness thereof, it is easy for metal powder to form due to abrasion.
Moreover, if the first shutter member 410 and the second shutter member 412 are formed of the same type of material, the hardnesses thereof at the region of abutment are of the same extent. This is a cause of noise arising at the time of the operations for opening and closing the opening 408.
Fourth, at the disk cartridge 400, the shutter main body 414 is merely accommodated rotatably between the bottom shell 404 (the case) and the cover member 420, and the shutter guide portion 416 is merely disposed slidably at the tubular wall 404A. In other words, the first shutter member 410 is not held at the bottom shell 404 (the case), and is merely prevented from falling out from the case by the cover member 420. Thus, at the time of assembling the disk cartridge 400 (at the time of assembling the respective parts before mounting the cover member 420), the first shutter member 410 cannot be prevented from falling out from the case.
Thus, at the time of assembling the disk cartridge 400, there is the need for complex and careful work to prevent the first shutter member 410 from falling out of the case, and the problem that the assembly workability is poor arises.
Similarly, at the disk cartridge 400, the rotation shaft 412C, which is provided at one end portion of the second shutter member 412, is merely inserted through the shaft hole 404B of the bottom shell 404 and the annular portion of the torsion spring 419. In other words, the second shutter member 412 is not held at the case, and is prevented from falling out from the case only by the cover member 420. Thus, at the time of assembling the disk cartridge 400 (at the time of assembling the respective parts before mounting the cover member 420), the second shutter member 412 cannot be prevented from falling out from the case.
Thus, at the time of assembling the disk cartridge 400, there is the need for complex and careful work to prevent the second shutter member 412 from falling out of the case, and the problem that the assembly workability is poor arises.
Fifth, in the disk cartridge 400, the rotation shaft 412C, which is fixed to one end portion of the second shutter member 412, is merely formed in a cylindrical shape. Therefore, it is easy for stress to concentrate at the root portion of the rotation shaft 412C (the portion thereof which borders on the flat plate portion of the second shutter member 412).
Thus, as was discussed previously in connection with the above-described first problem, if, for example, the disk cartridge 400 is dropped by accident, an impact force is applied between the shaft hole 404B and the rotation shaft 412C accompanying the relative movement between the second shutter member 412 and the bottom shell 404 (the case) due to the drop impact. This impact force concentrates at the root portion of the rotation shaft 412C, and is thus a cause of breakage of the second shutter member 412.
Further, the (planar portion of the) bottom shell 404 is generally formed as a thin plate. Thus, the aforementioned impact force is also a cause of breakage of the shaft hole 404B (i.e., the bottom shell 404).
In view of the aforementioned, an object of the present invention is to provide a shutter for a disk cartridge which has good slidability, is light-weight, and in which warping in the plate thickness direction thereof is suppressed.
Another object of the present invention is to provide a disk cartridge in which shutter members can be driven by an appropriate driving force so as to open and close an opening.
Yet another object of the present invention is to provide a disk cartridge which can prevent the occurrence of abrasion due to operation of shutter members.
Still another object of the present invention is to provide a disk cartridge in which assembly work is easy and which is low-cost.
A further object of the present invention is to provide a disk cartridge in which breaking of a rotation shaft of a shutter member can be prevented and reliability can be improved.
In order to achieve the above-described objects, in accordance with one aspect of the present invention, there is provided a shutter built-in in a disk cartridge, the disk cartridge comprising: a medium; a case having an access opening for access to the medium, and housing the medium; and a cover member having an opening which corresponds to the access opening, the cover member being mounted to an outer surface of the case, wherein the shutter being for opening and closing the opening and the access opening, and wherein the shutter is slidably provided between the outer surface of the case and the cover member, and is basically formed from a thin plate having a two layer structure formed from a metal layer and a resin layer. In accordance with another aspect of the present invention, there is provided a disk cartridge comprising: a medium having an axial center; a case having an access opening for access to the medium, and housing the medium; a cover member having an opening which corresponds to the access opening, and mounted to an outer surface of the case; and a shutter provided slidably between the outer surface of the case and the cover member, and for opening and closing the opening and the access opening, wherein the shutter is formed from a first shutter member and a second shutter member, wherein the first shutter member has a pushing portion for pushing and moving the second shutter member, wherein when the first shutter member rotates in one direction around the axial center of the medium, the first shutter member moves in a direction of opening the opening, and at this time, the pushing portion pushes the second shutter member and moves the second shutter member in a direction of opening the opening, and wherein the pushing portion projects by a predetermined dimension in a direction within a plane of movement of the first shutter member, in order to open and close the shutter.
In accordance with yet another aspect of the present invention, there is provided a disk cartridge comprising: a medium; a case having an access opening for access to the medium, and housing the medium; and a shutter for opening and closing the access opening, the shutter having a lightening portion at a region which does not impede a closing operation of the shutter. In accordance with still another aspect of the present invention, there is provided a disk cartridge comprising: a medium; a case having an access opening for access to the medium, and housing the medium; a cover member having an opening which corresponds to the access opening, and mounted to an outer surface of the case; and a shutter slidably provided between the outer surface of the case and the cover member, the shutter being for opening and closing the opening and the access opening, and the shutter having at least one projection for sliding with respect to at least one of the case and the cover member.
In accordance with yet another aspect of the present invention, there is provided a disk cartridge comprising: a medium; a case having an access opening for access to the medium, and housing the medium; and a shutter including a first shutter member and a second shutter member and being for opening and closing the access opening, and closing and opening operations of the shutter correspond to movements of the first and second shutter members in directions of relatively approaching one another and in directions of relatively moving away from one another, and the first shutter member has a pushing piece for the movements, and the second shutter member has a pushed piece for the movements, and the pushing piece and the pushed piece are formed from respectively different materials.
In accordance with another aspect of the present invention, there is provided a disk cartridge comprising: a medium; a case having an access opening for access to the medium, and housing the medium; and a shutter including a first shutter member and a second shutter member and being for opening and closing the access opening, and closing and opening operations of the shutter correspond to movements of the first and second shutter members in directions of relatively approaching one another and in directions of relatively moving away from one another, and the first shutter member has a pushing portion for the movements, and the second shutter member has a pushed portion for the movements, and the pushing portion and the pushed portion are formed from a resin material having abrasion resistance and a low coefficient of friction.
In accordance with yet another aspect of the present invention, there is provided a disk cartridge comprising: a medium; a case having an access opening for access to the medium, and housing the medium; and a shutter which opens and closes the access opening, and which has an engaging portion for preventing the shutter from falling out from the case at a time of opening and closing operations of the shutter.
In accordance with still another aspect of the present invention, there is provided a disk cartridge comprising: a medium; a case having an access opening for access to the medium, and housing the medium; and a shutter which opens and closes the access opening, and which has an engaging member which is rotatably connected to the case via a supporting structure formed from a rotation shaft and a shaft hole and which prevents the shutter from falling out from the case.